Optical navigation systems operate to estimate movements between the optical navigation systems and target surfaces to perform tracking operations. An optical navigation system uses a light source, such as a light-emitting diode (LED) or a laser diode, to illuminate a region of a target surface and an image sensor to receive the light reflected from the target surface to successively capture frames of image data of the target surface. The optical navigation system compares the successive image frames and estimates the relative movements between the optical navigation system and the target surface based on the comparison between the current image frame and a previous image frame. The comparison is based on detecting and computing displacements of features in the captured frames of image data.
Optical navigation systems are commonly used in optical computer mice to track the movements of the mice relative to the surfaces on which the mice are manually manipulated. The movements of a computer mouse are used to control a cursor on a monitor of a computer system. An important consideration for an optical navigation system for use in an optical mouse is the intensity of the illuminating light provided by the light source of the optical navigation system. The illuminating light provided by the light source should be of sufficient intensity to illuminate different types of surfaces so that the optical navigation system can properly perform tracking operations for optical mouse movements up to a predefined rate of speed. However, the amount of illuminating light needed for different types of surfaces differs depending on the brightness of these surfaces. Brighter surfaces require less intense illuminating light than darker surfaces.
A concern with conventional optical navigation systems is that most of the conventional systems use a single drive current to drive the light source, and thus, provide an illuminating light of substantially constant intensity. However, since the illuminating light must work well for different types of surfaces, including darker surfaces, the drive current is set higher than necessary for most bright surfaces. Therefore, when operating on bright surfaces, these conventional optical navigation systems waste valuable power with respect to generation of the illuminating light.
In view of this concern, there is need for a system and method for performing optical navigation that works well for different type of surfaces while reducing power consumption.